Negative electrode for primary cells



Dec. 23, 1958 J. MoYNs NEGATIVE ELECTRODE FOR PRIMARY CELLS Filed May 21. 1953 FIG.2

JUL 5 M0 YA/S @WMM nited States rvan alkaline electrolyte,` togive of which the French application, tiled April lz,s-ss',977 NEGATIVE'ELECTRODE FR PREMARY CELLS `inles Moyns," Poitirs,"ll`rance, 'assigner'tol'Societe'de la Pile Leclan'ch, Chasseneuil ``du Poitou (Vienne), France, a corporation of France AppncaaonMay 21, i953, sensi Nessuno; 9 creams. ici.l lssrzs) vpassivationand inversion which `occurs in` primary cells having av positiverand a negative electrode and-anl alkam line electrolyte therebetween.

v As described in this Frenchpatent, the vphenomenon ,.ofrpassivationisdue to a superficial modication-of the negative electrode. Since, ordinarily, 'aside from such passivation:phenomenon,r primary cells of the .type describedv hereinabove stilloffer a considerable useful life in that the normal possibilities of the different constitulents of the cell are far from being exhausted, this French 'patent provides va solution of counteracting orfpreventing such passivation. l p

For that purpose, the French Patent 1,001,750 suggests that the paths of'ionic exchanges between the-electrodes be so arranged as to havevaried lengths. ln accordance with this French patent, this is obtained by providingacirculr positive electrode' and a non-circular negative electrode surro-u'lrdin'g'the`saine.l According to tive electrode for use in a primary cell provided with a positive electrode surrounded the parallelepipedf-is reinforced vthereof so as to' increase the densityy of ionic exchanges 2. 1 to`3 for another'non-limitative exampleof a negative electrode according to the present invention.

The present invention essentially yconsists-of a negaby the negative electrode and with an alkaline electrolyte whereby the negative .-electrode is made in onel piece, for example, by casting metals such as zinc in a mold rof suitable shape orby extrusion-methods with cer-tain elements of the electrode attached thereto in any suitable manner, `such negative electrode being so shaped'as to produce in cooperation with the positive electrode paths of ionic exchangeshaving different lengths and being provided at the lower'portion thereof with a plurality of recesses formed by cross pieces rigidly connectedy or formed integrallywith--the negative electrode.

As shown in Figures 1 to 3, the positive electrode of suitable construction as disclosed in the French Patent 1,001,750 is surrounded by the negative electrode which comprisesa main portion y-in the shape of a straight parallelepipedal tube 10 theangles or-corners of which l1 may be rounded; the faces of said electrode may be plane or preferablyconcave, and the thickness'ofeach face of in the middle portion'lZ Thev main portion 10 comprises, at its lower portion, a series of recesses13 formed'by crosspieces placed per pendicularly to one anothersoas to form-squares in the central area.

The metal forming these recessesrlS iscast integral ,with the main portion-10, i.--e. the assembly of thesoluble electrode and its recesses is'inone piece.

This series of recesses-13 isplaced in locations and at distances remote from-fthe depolarizingagglomerate, so

a modified embodiment of' thisiFrench patent, both the `positive and negative'elec'trodesare circular. However,

the negative electrode Y"may vbefprovided with' in the upper part thereof to eiectlvely produce different lengths for the ionic exchanges.

apertures The present invention relates to an improvement of the negativer electrode in accordancewith the teachings of a primary cell of the type described in the French patent, and more particularly, to a negative electrode cast integrally or made of one piece to further enhance and improve the benecial results obtained thereby.

It is accordingly an object of the present invention to provide a negative electrode for cells using an alkaline electrolyte and a positive electrode as described, for example, in the French Patent 1,001,750, characterized in that it comprises a tubular portion comprising, at its lower portion, a series of recesses formed by crosspieces leading to said tubular electrode.

The invention will be better understood from the fo lowing description with reference to the appended drawing wherein:

Figure l is a plan View of a negative electrode accordpaths of p that the currentdensity 'therethrough is less than on the parallelepipedal portion. Shouldv the passivation'lof the cell tend to occur in areas subjected to'a heavy current density, it will be counteracted bythe presenceyon the same negative electrode, fof low current density areas.

` Due to 'this lesserfparticipationein ionic exchanges of the lower' portionl vof the negative velectrode with respect to the upper portion, the amount ofavailable metal may be decreased thereat, -Figu'resZ and 3 show the correspending variation in thickness ofthe metal, generally zinc.

For connecting thev cell `with the outside circuit, there provided, in one of the dihedrons 11 a boss lldwhich, 'owing to its' shape, also helps to counteract passivation; the negative connection may be fastenediin recess 15 of the bos's 14.

The positive electrode 21 may be again of any suitable construction as shown in the aforementioned French patent, and the negative electrode in Figures 4 to 6 has a shape similar to that of the electrode of Figures 1 to 3; it differs therefrom by the shape of the recesses formed by parallel and unidirectional crosspieces.

Other variations in the shapes of the negative electrode and its recesses may be imagined without any diiculty, in accordance with the main inventive concept of the present invention as defined at the beginning of the present specification, as well as in the main French Patent 1,001,750; For example, the angles or corners 11 may form non-rounded-off corners. Furthermore, the recesses 13 could also be made to have shapes ditferent from the square shape in Figure l, for example, in the shape of rectangles, rhombus, or any other suitable, preferably symmetrical, shape.

The manufacture of such an electrode may be effected simply in one piece by casting metal in a mould of suitable shape; this same electrode, however, could also be manufactured by modern extrusion methods, certain elements of the electrode being then attached thereon by soldering or any other means, and this within the scope of the present invention. I p

According to the present invention it is possible to help preventing the passivation of the negative electrode by causing different crystallizations in the various areas of the electrode; for instance, the main'portion 10-may be given a different crystallization from that assigned to the portion comprising the series of recesses `13.

This result is easily achieved when the4 electrode is manufactured by casting; the `two portions o-f the electrode are subjected to different cooling speeds. The same result is obtained by annealing of a predetermined portion of the electrode which modifies the initial crystallization. f

Finally, according to the present invention, another means is provided for opposing passivation by creating different potentials over the surface of thenegative electrode, by amalgamating the surface lwith-variable mercury contents according to the electrode area. ence of mercury causes potential variations in each area of the negative electrode, due, on the one hand, to the mercurys own potential, and, on the other han-d, to changes in the crystallization of the negative electrode metal caused by the action of this mercury.

The amalgamation of the electrode is obtained by conventional means applied in such a manner as to give the The presdesired result: for instance, the use of a mercuric chloride solution of a given concentration, in whichvarious portions of the negative electrode are immersed during different times; or by using during the same time, mercurio chloride solutions with diierent concentrations.

What is claimed is:

1. A unitary negative electrode made of one piece for use with a primary .cell having a positive electrodel and an alkaline electrolyte, said negative and positive electrode being of such shape as to provide paths for the ionic exchange therebetween of varied lengths, said nega'Y tive electrode being intended to prevent polarization during discharge thereof and comprising a substantially unitary tubular member having a main portion operative at relatively high current densities and `another auxiliary portion near one end thereof operative at relatively low current densities to counteract passivation of said negative electrode and to minimize the ohmic resistance between Said main and auxiliary portions, and a plurality of cross pieces forming partitions extending essentiallyA parallel to the axial direction of said tubular member" and being rigidly connected with said another portion 'Y of said tubular member along the inside thereof to thereby reinforce said tubular member at the height of said auxiliary portion.

. 2. A unitary negative electrode according to claim l, wherein said cross pieces are constituted by a series of orthogonal partitions.

3. A unitary negative electrode according to claim 1, wherein said cross pieces are constituted by a series of partitions parallel with respect to each other.

4. A negative electrode according to claim 1 wherein the thickness of the wall of said tubular member forming said negative electrode decreases from an upper portion to the lower extremity thereof at the lower side of said partitions.

5. A negative electrode according to claim 1 wherein said tubular part is a straight tube of quadrangular cross section with walls of concave shape as seen in a plane perpendicular to the axis of said tubular member.

6. A negative electrode according to claim 1 wherein said tubular` member is of quadrangular cross section `and wherein the thickness of the wall `of said tubular member is a maximum .in the center portion of each of the four sides thereof and decreases toward the` respective corners thereof as seen in a plane perpendicular to the axis of said tubular member.

7. A negative electrode according to claim l wherein the tubular member is formed by a straight tube of quadrangular cross section with walls of concave shape in a plane perpendicular to the axis of said tubular'member, the thickness of each side of said tubular member being a maximum in the middle portion thereof and decreasing toward the respective corners as viewed in a plane perpendicular to the axis of said tubular member.

8. A negative electrode according to claim 1 wherein the tubular member of the negative electrode is formed by a straight tube of rectangular cross section,and wherein one of the vertically edged dihedrons of said straight tube includes at the apex thereof a reinforcing boss for attaching the electrical connection.

9. A negative electrode according to claim 8 wherein the dihedrons of the quadrangle are rounded off at the apexes.

References Cited in the le of this patent UNITED STATES PATENTS 1,267,349 Smith May 21, 1918 1,725,592 Mertesv Aug. 20, 1929 2,085,269 Oppenheim June 29, 1932 2,118,712 t Oppenheim May 24, 1938 2,629,758 Ruben Feb. 24, 1953 FOREIGN PATENTS 587,470 Great IBritain Apr. 28, 1947 68,276 Denmark Ian. 3, 1949 1,001,750 France Oct. 24, 1951 

1. A UNITARY NEGATIVE ELECTRODE MADE OF ONE PIECE FOR USE WITH A PRIMARY CELL HAVING A POSITVE ELECTRODE AND AN ALKALINE ELECTROLYTE, SAID NEGATIVE AND POSITIVE ELECTRODE BEING OF SUCH SHAPE AS TO PROVIDE PATHS FOR THE IONIC EXCHANGE THEREBETWEEN OF VARIED LENGTHS, SAID NEGATIVE ELECTRODE BEING INTENDED TO PREVENT POLARIZATION DURING DISCHARGE THEREOF AND COMPRISING A SUBSTANTIALLY UNITARY TUBULAR MEMBER HJAVING A MAIN PORTIN OPERATIVE AT RELATIVELY HIGH CURRENT DENSITIES AND ANOTHER AUXILIARY PORTION NEAR ONE END THEREOF OPERATIVE AT RELATIVELY LOW CURRENT DENSITIES TO COUNTERACT PASSIVATION OF SAID NAGATIVE ELECTRODE AND TO MINIMIZE THE OHMIC RESISTANCE BETWEEN SAID MAIN AND AUXILIARY PORTIONS, AND A PLURALITY OF CROSS PIECES FORMING PARTITIONS EXTENDING ESSENTIALLY PARALLEL TO THE AXIAL DIRECTION OF SAID TUBULAR MEMBER AND BEING RIGIDLY CONNECTED WITH SAID ANOTHER PORTION OF SAID TUBULAR MEMBER ALONG THE INSIDE THEREOF TO THEREBY REINFORCE SAID TUBULAR MEMBER AT THE HEIGHT OF SAID AUXILIARY PORTION. 